The present disclosure pertains generally to firearms. In particular, the present disclosure provides an improved cam pin for a bolt carrier system of a firearm.
The M16 rifle is a standard weapon of choice for many institutions around the world including the U.S. military and many law enforcement agencies. Over the years the M16 has been modified to include a large family of weapons including semi-automatic counterparts which are popular in the civilian sector. Additionally, the M16 design has been scaled up from a .223 (5.56 mm) caliber bullet to 7.62 mm NATO and .308 Winchester as well as shortened into the more compact M4 carbine version of the M16.
Generally, the M16 family of automatic and semi-automatic rifles is based on a gas operated rotating bolt carrier system. The bolt carrier includes a multi-lug bolt that interlocks with corresponding lugs within a barrel extension engaged to the barrel to contain the firing of each round of ammunition. The bolt carrier system includes a rotating mechanism that locks the bolt into place with respect to the barrel extension during the loading step and also includes a corresponding unlocking motion when extracting a spent casing. The bolt includes a spring loaded extractor configured to releasably engage a cartridge as it is loaded into the firing chamber. When the rifle is fired, the interlock bolt contains the firing force by transmitting the force through the lugs to corresponding lugs of the barrel extension.
When a round is fired, gas pressure is vented from a port in the barrel down from the firing chamber and that gas pressure is applied to the bolt carrier system to impart energy in a rearward direction. As the bolt carrier system moves rearwardly, it first rotates the bolt to unlock the bolt lugs from the barrel extension lugs. Then, as it further recoils, the extractor pulls the expended cartridge from the firing chamber. Once the cartridge clears the firing chamber an ejector in the bolt pivots the cartridge about the extractor and ejects the spent cartridge, as is well known in the art. As the bolt carrier system continues to move rearwardly its travel is halted by a spring that then pushes the bolt carrier system forward to engage and chamber another round. This process is repeated as often as desired by a shooter until the last cartridge in a magazine is expended.
Under repeated firing and cycling of the bolt carrier system, some components of the bolt carrier system slide and impact other components of the bolt carrier system, causing wear on at least some of the components. In particular, cam pins of existing bolt carrier systems have been found to suffer from wear which may lead to failure of the cam pin. Thus, there is a desire for cam pins that are wear resistant.